Pistons are parts that are vulnerable to friction, and cause 30 to 50% of engine frictional energy losses. Particularly, the piston's reciprocation causes friction with the internal surface of the cylinder under a pressure of 30 to 40 MPa during an explosion stroke of the engine. Resin including a solid lubricant, such as graphite and MoS2, can be applied on the surface of the piston skirt in order to minimize frictional losses.
A PTFE coating solution has been used as a coating agent or a lubricant in the industrial world. For the PTFE coating solution, diamond powder is subjected to bead milling, dispersed in an organic solvent, and mixed with a silane solution to surround the diamond powder particles with the silane solution to manufacture a mixture solution including the diamond powder particles. In such a solution, the diamond powder particles are not agglomerated but dispersed to have a nano size within the solution, and a PTFE (polytetrafluoroethylene) solution having an excellent low-friction property is then added to the mixture solution to obtain the PTFE coating solution.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.